482 



The spring curve )B a very smooth one, and lias also a smaller amplitude th;m the curve of any other 

 season. It rises from a minimum at "> a.m. to a maximum at 11 a.m., and then, after a slight fall for six or 

 seven hours, it rises to the maximum of the day at 11 p.m. 



The Fourier coefficients of the diurnal variation for the seasons, which are given in Table IV., differ from 

 those of lower latitudes in the relatively large amplitude of the first component. The epochs of the 

 maximum of this component in the different seasons become progress] vrl v earlier as the year grows, and 

 then get later again through the autumn to the winter, which appears to indicate some relation to the Sun's 

 declination. But the fact that in these latitudes a diurnal variation exists all the year through is a point 

 of some interest, because it has hitherto been pretty generally assumed that it disappeared entirely at a 

 much lower latitude than 70 degrees. 



TABLE IV. Fourier Coefficients of Diurnal Inequality of Pressure. 



RANGE OF PRESSURE. 



The mean pressure in the Antarctic is low, and in every month of the two years during which the 

 " Discovery " remained at Ross Island the minimum fell below 29 inches, whilst the maximum seldom 

 reached 30 inches and never greatly exceeded it. The lowest point reached by the mercury was 

 28-140 inches in June, 1902, and the highest 30 - 181 inches in May of the same year, giving a maximum 

 range of just over 2 inches. The largest range in any month occurred in June, 1902, and amounted to 

 1-804 inches, but on three other occasions May and July, 1902, .and August, 1903 it exceeded 

 1'7 inches. In 1902 the monthly range exceeded an inch in the eight consecutive months April to 

 November, but in the following year so large a range occurred only in the five months June to October. 

 The average monthly range for the two years amounted to 1-154 inches. 



A quickly falling barometer was frequently, but not invariably, associated with relatively high 

 temperature, and conversely an increase of pressure commonly brought with it an increase of cold. 



The fall of the barometer which preceded many of the storms was not very large if judged by Western 

 European experiences. 



